Egg white is the clear, gelatinous liquid that surrounds the yolk inside the egg. Also called the albumen, egg white serves as a shock-absorber and anchor for the egg yolk and provides nutrients to the developing embryo (in fertilized eggs). It's also an incredibly nutritional food. Unlike egg yolk, the egg white is free of fats and cholesterol and a great source of protein.

For many years, whole eggs got a bad rap among health professionals because they are high in cholesterol thanks to the egg yolk. Historically, excess cholesterol in the diet was associated with myriad health issues. However, recent research has dissolved this assumption to an extent, and many health professionals now consider eggs a healthy food option.

"Eggs are all-natural and provide one of the highest quality proteins of any food available. One egg provides more than six grams of protein, or 13% of the recommended Daily Value," said Mitch Kanter, executive director of the Egg Nutrition Center, the research arm of the American Egg Board.

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Nutrition facts

Here are the nutrition facts for egg white from 1 large egg, according to FoodData Central of the U.S. Department of Agriculture (USDA):

What's in egg white?

Egg whites are good sources of riboflavin and selenium, Kanter told Live Science. Additionally, each egg white contains 54 milligrams of potassium, an essential mineral, and 55 mg of sodium. Too much sodium can cause problems, but a moderate amount of it (about 1,500 mg per day, according to Nutrition Today) is essential for body functioning.

Egg whites are also considered a low-calorie food. One large egg contains 55 calories in its yolk, but just 17 in its whites, according to the U.S. Department of Agriculture. They contain no saturated fat or cholesterol, making them a popular choice for those watching their cholesterol levels or at risk of diabetes or heart disease. Egg whites contain very little carbohydrates and do not contain sugar.

Are egg whites good for you?

For a long time whole eggs were seen as the bad guy because they're high in cholesterol. But according to the Harvard School of Public Health, "a solid body of research shows that for most people, cholesterol in food has a much smaller effect on blood levels of total cholesterol and harmful LDL cholesterol than does the mix of fats in the diet."

Additionally, the Mayo Clinic asserts that it is generally fine for healthy people to eat six or seven whole eggs per week. Whole eggs, including egg whites, are generally considered part of a healthy diet for most people.

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The case is different for people with diabetes, high cholesterol or hypertension. Studies have shown that diabetics who eat whole eggs regularly are more likely to develop heart disease. For example, a 2010 analysis published in the Canadian Journal of Cardiology reported that participants in the Physicians' Health Study who became diabetic during the course of the 20-year study were twice as likely to develop cardiovascular disease if they ate one egg per day. It also stated that new cases of diabetes were more likely for those who ate eggs regularly.

However, egg whites lack the cholesterol that may cause health issues, making egg whites a better dietary choice for people at risk of diabetes, high cholesterol or heart disease.

What are the benefits of egg whites?

Egg whites are an excellent source of protein, with 3.6 grams of protein per 17-calorie egg white. "High-quality protein helps build muscles and allows people to feel full longer and stay energized, which can help them maintain a healthy weight," Kanter said.

"Although we often think of protein’s function in building and maintaining muscle, newer research suggests other benefits of protein," he said. For example, numerous studies have found that protein-rich breakfasts, including those containing eggs, result in damped blood glucose and insulin responses, greater feeling of fullness, and lower energy intake at a subsequent meal, he said. These data suggest that regular egg consumption can help with health weight management.

"Diets higher in protein have been linked with lower risk of developing hypertension," Kanter said, and research shows that egg whites might be particularly helpful. At a 2013 meeting of the American Chemical Society, scientists from Clemson University announced they had discovered that a component of the protein found in egg whites "reduces blood pressure about as much as a low dose of Captopril, a high blood pressure drug."

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One large egg white contains 54 mg of potassium, a vital mineral and electrolyte associated with heart health, bone health and overall effective cell and organ functioning.

Egg whites contain almost the same amount of sodium, another mineral that works together with potassium to create an essential electrochemical gradient across cells known as membrane potential, according to the Linus Pauling Institute at Oregon State University. Membrane potential is critical for proper muscle contraction, nerve impulse transmission, heart function, and transferring nutrients and metabolites throughout cells.

Kanter also noted that egg whites are a good source of riboflavin, also called vitamin B2. This vitamin is associated with healthy metabolism and red blood cell production, according to the National Institutes of Health, which lists eggs on its list of good sources of riboflavin. It also works as an antioxidant, breaking down dangerous free radicals (molecules that can damage or kill cells), according to the University of Maryland Medical Center.

Which is healthier: egg yolk or egg white?

The answer is both.

While egg whites are a good source of protein and a great option for those suffering from diabetes, high cholesterol or cardiovascular disease, egg whites don't provide all the same nutritional benefits of whole eggs. That's because most of the vitamins and minerals present in eggs are contained in the yolk, Kanter said. “Nutrients found exclusively in the yolk include choline, vitamin B12, vitamin D and iron, among others.”

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Regular consumption of egg yolk also supports good eye health. A 2005 study published in The Journal of Nutrition found that two of the chemicals critical for combating macular degeneration – lutein and zeaxanthin – are also present in egg yolks and accumulate in the retina after consumption.

So for most people, eating the whole egg is healthier than eating the egg white or egg yolk alone.

Additional resources

Eggs can be contaminated by a bacteria called Salmonella. Learn more about how to consume eggs safely from FoodSafety.gov. Learn the difference between cage-free and traditional battery-cage eggs from The Humane Society of the United States. Learn how the U.S. Department of Agriculture measures cage-free egg quality through their grading system.This article is for informational purposes only, and is not meant to offer medical advice.